Haemophilia is an inherited disease which has been known for centuries but it is only within the last four decades that it has been possible to differentiate between the various forms; haemophilia A, haemophilia B and haemophilia C. Haemophilia A is the most frequent form. It affects only males with an incidence of one or two individuals per 10,000 live-born males. The disease is caused by strongly decreased level or absence of biologically active coagulation factor VIII (antihaemophilic factor), which is a protein normally present in plasma. The clinical manifestation of haemophilia A is a strong bleeding tendency and before treatment with factor VIII concentrates was introduced, the mean age of those patients was less than 20 years. Concentrates of factor VIII obtained from plasma have been available for about three decades. This has improved the situation for treatment of haemophilia patients considerably and given them possibility to live a normal life.
It is commonly recognized that the severity of haemophilia A and B, can be divided into three categories: severe, moderate and mild. In severe haemophilia A, the plasma level of factor VIII activity in the blood is less than 1% of the normal plasma level. In moderate haemophilia A, the plasma level of factor VIII activity in the blood is in the range of from 1 up to 4% of the normal plasma Level. In mild haemophilia A, the plasma level of factor VIII activity in the blood is in the range of from 5 up to 25% of the normal plasma level. The normal plasma level of factor VIII activity in the blood is defined as 1 IU/ml of blood Severe, moderate and mild haemophilia B, are defined by the same plasma levels as those given for factor VIII above. The normal plasma level of factor IX activity in the blood is defined as 1 IU/ml of blood Reference is here made to Inga Marie Nilsson in Hemophilia, Pharmacia Plasma Products, Stockholm, Sweden, p. 2-3, 1994.
A medicament with a very large and labile molecule, such as coagulation VIII with a molecular mass of 170 to 300 kDa, is normally given intravenously since these medicaments normally exhibit a very low bioavailability due to insufficient absorption and severe degradation, if given subcutaneously, intramuscularly or intradermally. Thus, a factor VIII concentrate dissolved in sodium citrate and injected intramuscularly yielded a maximum circulating level of only 1.4% of the normal plasma level (Pool et al, New England J. Medicine, vol. 275, no. 10, p. 547-548, 1966). The studies further revealed that there was no significant difference in the activity recovered in the circulation regardless of whether such citrate was added to the preparation. In a later study, a high-purity factor VIII was administered intramuscularly to haemophilic dogs and human volunteers (Johnson et al, Br. J. Hematology, vol. 21, p. 21-41, 1971). Although, the doses were much larger than used by Pool et al, neither the dogs nor the human volunteers showed a significant rise in plasma factor VIII levels. In fact, the plasma factor VIII concentration in the haemophilic human volunteers remained below 1% of the normal plasma level, i.e. the severe haemophilia A prevailed even after administration in the absence of additives increasing the bioavailability.
Various additives have been proposed for enhancing the absorption of a great number of pharmaceuticals, including small molecules such as insulin and peptide fractions of factor VIII. Thus, WO-A-92/01440 relates to use of dimethyl-.beta.-cyclodextrin for enhancing transmucosal administration of insulin with a molecular mass of about 5,800 Da. Information pertaining to transport of small molecules by non-invasive routes, cannot be transferred to transport of large molecules to the intravenous circulation by subcutaneous, intramuscular or intradermal administration. This is especially true, since the aim of WO-A-92/01440 is to make superfluous injections of (poly)peptides or proteins. Furthermore, before intramuscular administration saline is used for dissolving peptide fractions of factor VIII with a molecular mass of from 1,000 to 20,000 Da (Conte et al, Arzneim.-Forsch./Drug Res., vol. 39 (I), no. 4, p. 463-466, 1989). Here, also, the experiments relate to small molecules yielding an unknown bioavailability since the activity of the peptide fractions of factor VIII has not been determined.
EP-A-0 522 491 relates to use of a water-soluble species of hyaluronic acid in combination with a water-soluble protein showing no substantial pharmacological activity for enhancing administration of a pharmacologically active polypeptide. Blood clotting factors are mentioned amongst a great number of polypeptides. Furthermore, there are no examples showing the possible effect of hyaluronic acids upon a administration of any blood clotting factor e.g. by injection
JP-A-63-063624 relates to use of collagen for providing slow release of an unspecified drug upon e.g. subcutaneous administration.
JP-A-56-127308 relates to emulsions containing blood-coagulation factor VIII, soybean oil and phospholipids. The object of these emulsions is to eliminate the problems encountered with conventional parenteral administration. The emulsions are therefore administered orally, which is shown in several of the examples.
Factor VIII can also be used for other therapeutic purposes than for treating haemophilia A. Thus, WO-A-93/24137 relates to formulations Factor VIII intended for intradermal or topical administration as an antiinflammatory agent. The formulations are intended for local administration to non-haemophilic human bodies and not to the intravenous circulation of humans suffering from haemophilia A. The therapeutic effect is thus local and not systemic, the latter being required to alleviate haemophilia A.
Subcutaneous administration of factor VIII without additives is known from Berett et al, Am. J. Hematology, vol 47, no. 1, p. 61-62, 1994. Factor IX is a smaller molecule than factor VIII having a molecular mass of about 56 kDa. The human factor IX was poorly and very slowly transported into the circulation, when injected into the subcutaneous tissue of hemophilia B patients. This is in agreement with the results obtained with factor VIII.
The presently available factor VIII and factor IX preparations on the market are made as a formulation for intravenous administration and the majority of the factor VIII preparations are stabilized with human serum albium.
Large and viable proteins are thus normally given intravenously so that the medicament is directly available in the blood stream. It would however be advantageous if a medicament could be given subcutaneously, intramuscularly or intradermally as these administration forms are much easier to handle for the patient. Especially if the medicament must be taken regularly during the whole life and treatment is to start early, already during the patients first year of life.